We reported previously the first randomized study of any kind in patients with nonmetastatic, castrate-resistant prostate cancer. The study employed vaccine, the hormone nilutamide, and the combined therapy (crossover for each arm) with an endpoint of time to progression. We now report survival analyses at 6.5 years from the initiation of therapy with a median potential follow-up of 4.4 years. Forty-two patients were randomized to receive either a poxvirus-based prostate-specific antigen (PSA) vaccine or nilutamide. Patients in either arm who developed increasing PSA without radiographic evidence of metastasis could cross over to receive the combined therapies. Median survival among all patients was 4.4 years from date of enrollment. Median survival exhibited a trend toward improvement for patients initially randomized to the vaccine arm (median, 5.1 versus 3.4 years;P = 0.13). Starting from the on-study date, the retrospectively determined subset of 12 patients who initially received vaccine and then later received nilutamide suggested improved survival compared with the 8 patients who began with nilutamide and subsequently were treated with vaccine (median, 6.2 versus 3.7 years;P = 0.045). A subgroup analysis of patients randomized to the vaccine arm versus the nilutamide arm showed substantial improvements in survival if at baseline patients had a Gleason score less than 7 (P = 0.033) and PSA less than 20 ng/dL (P = 0.013) or who had prior radiation therapy (P = 0.018). These data indicate that patients with nonmetastatic castration-resistant prostate cancer (D0.5) who receive vaccine before second-line hormone therapy may potentially result in improved survival compared with patients who received hormone therapy and then vaccine. These data also suggest that patients with more indolent disease may derive greater clinical benefit from vaccine alone or vaccine before second-line hormone therapy compared with hormone therapy alone or hormone therapy followed by vaccine. These findings have potential implications for both the design and endpoint analysis of larger vaccine combination therapy trials. We hypothesized that a metronomic dose of IL-2 as a biological adjuvant would cause less toxicity while maintaining immunologic response. Eighteen patients with localized prostate cancer were treated in a single arm trial using previously established doses of vaccine and radiation therapy. The vaccine used was a recombinant vaccinia virus engineered to encode PSA admixed with a recombinant vaccinia encoding the costimulatory molecule B7.1, followed by booster vaccinations with a recombinant fowlpox vector expressing PSA. Patients received a total of eight planned vaccination cycles, once every 4 weeks, with granulocyte-macrophage colony-stimulating factor given on days 1to 4 and IL-2 at a dose of 0.6MIU/M2 given from days 8 to 21 after each vaccination. Definitive external beam radiation therapy was initiated after the third vaccination cycle. Patients were evaluated for safety and immunologic response. Toxicity and immunologic activity were compared with the previously reported regimen containing a higher dose of IL-2. Seventeen of 18 patients received all eight cycles of vaccine with IL-2. Five of eight HLA-A2+ patients evaluated had an increase in PSA-specific T cells of greater than or equal to 3-fold. Toxicities were generally mild, with only seven vaccination cycles of 140 given resulting in grade 3 toxicities possibly attributable to IL-2. Metronomic-dose IL-2 in combination with vaccine and radiation therapy is safe, can induce prostate-specific immune responses, and has immunologic activity similar to low-dose IL-2, with markedly reduced toxicities. Dr. Gulley and his colleagues in the Laboratory of Tumor Immunology and Biology (LTIB) and the Medical Oncology Branch (MOB), Center for Cancer Research (CCR), NCI, have ongoing or recently completed in FY08-09 the following collaborative vaccine clinical trials at the NCI Clinical Center. A Phase I/II pilot study of sequential vaccinations with rFowlpox-PSA (L155)-TRICOM (PROSTVAC-F/TRICOM) alone, or in combination with rVaccinia-PSA (L155)-TRICOM (PROSTVAC-V/TRICOM), and the role of GM-CSF, in patients with prostate cancer, MOB, CCR, NCI. This is the first trial involving the use of a vaccine for prostate cancer containing transgenes for three costimulatory molecules. The study showed evidence of significant drops in serum PSA, objective response, prolonged stable disease and survival in patients with advanced prostate cancer which correlated with immunologic responses. This trial also provided evidence for a more appropriate prostate cancer patient population for vaccine therapy trials. A randomized Phase II trial combining vaccine therapy with PROSTVAC/TRICOM and Flutamide, vs. Flutamide alone in men with androgen insensitive non metastatic (D0.5) prostate cancer, MOB, CCR, NCI. This was the first randomized trial to combine a vaccine with this second-line hormone therapy in D0.5 prostate cancer patients. Phase I Trial of a PSA based vaccine and an anti-CTLA-4 antibody in patients with Metastatic Androgen Independent Prostate Cancer. This trial is the first clinical trial to combine an anti-CTLA-4 antibody and a vector-based vaccine in prostate cancer. A randomized phase 2.5 study of 153Sm-EDTMP (Quadramet) with or without a PSA/TRICOM vaccine in men with androgen-insensitive metastatic prostate cancer, MOB, CCR, NCI. This trial is the first clinical trial to combine vaccine with a bone seeking radionuclide for use in patients with androgen independent prostate cancer. A randomized Pilot Phase II study of Docetaxel alone or in combination with PANVAC-V (vaccinia) and PANVAC-F (fowlpox) in adults with metastatic breast cancer. MOB, CCR, NCI. This is the first randomized trial to combine vaccine with Docetaxel in this breast cancer patient population. A Phase I-II study of tumor vaccine following chemotherapy in patients with previously untreated metastatic breast cancer: Vaccine-induced bias of T-cell repertoire reconstitution after T-cell Reinfusion. (Collaboration with Dr. Sportes) MOB, CCR, NCI. This trial combines the concepts of T-cell repertoire reconstitution with vaccine therapy. An open label pilot study to evaluate the safety and tolerability of PANVAC-V (Vaccinia) and PANVAC-F (Fowlpox) in combination with Sargramostim (GM-CSF) in patients with metastatic adenocarcinoma, MOB, CCR, NCI. This trial employed vectors with transgenes of both multiple tumor antigens and multiple costimulatory molecules. A recent amendment allowed additional patients to further analyze the efficacy of the vaccine. Collaborative Trials with Extramural Cancer Centers A phase II study of PROSTVAC-V(Vaccinia)/TRICOM and PROSTVAC-F(fowlpox)/TRICOM with GM-CSF in patients with PSA progression after local therapy for prostate cancer. (Eastern Cooperative Oncology Group) A Phase I study of sequential vaccinations with fowlpox-CEA(6D)-TRICOM and vaccinia-CEA(6D)-TRICOM, in combination with GM-CSF and Interferon-Alfa-2B in patients with CEA expressing carcinomas. (Ohio State Comprehensive Cancer Center) A Phase I study of regulatory T cell depletion with Denileukin Diftitox followed by active immunotherapy with autologous dendritic cells infected with CEA-6D expressing fowlpox-TRICOM in patients with advanced or metastatic malignancies expressing CEA (Duke Comprehensive Cancer Center) Phase I study of intravessical recombinant fowlpox-GM-CSF and or recombinant fowlpox-TRICOM in patients with bladder carcinoma scheduled for cystectomy (Cancer Institute of New Jersey, CINJ)